The squeeze pump so far known in the art is shown in FIG. 1 and comprises a resilient tube 2 bent arcuately and placed along the inner periphery of the pump casing 1, and a plurality of presser rolls 5 carried by end parts of rotary arms 4 parallel to a rotary arbor 3 integral with said rotary arm 4. Upon rotation of the rotary arm 4 in the direction of the arrow mark in FIG. 1, the respective presser rolls 5 on the resilient tube 2 whilst the tube 2 is clamped between the rolls 5 and the inner periphery of the pump casing 1, for transferring the slurry in the tube 2.
However, in this known type of the squeeze pump, since the resilient tube 2 is pressed by the presser rolls 5 onto the inner peripheral surface of the pump casing 1, such peripheral surface must be accurately arcuate for stably clamping said resilient tube 2 between the presser rolls 5 and the inner peripheral surface of the pump casing 1. Moreover, to prevent the damage of the resilient tube 2, such peripheral surface must be ground to a smooth surface, while the rotary shaft 3 must be centered accurately in the pump casing 1 so that said presser rolls 5 may accurately follow the inner peripheral surface of the pump casing 1.
On the other hand, when the resilient tube 2 is mounted in the casing 1 in an arcuate form along the arcuate surface, the tube 2 may be elliptical in cross-section and moreover the tube 2 is pressed by the rolls 5 is a direction to further flatten out the ellipsis. As a result, the tube 2 may be restored simply to an elliptical cross-section after passage through the presser rolls 5. Thus the tube 2 may be deformed permanently to an elliptical cross-section with prolonged use resulting in the reduction of the slurry quantity to be transferred. In addition thereto, since the tube 2 is pressed onto the inner peripheral surface of the pump casing 1, the tube 2 tends to be elongated slightly and heated due to strong friction caused by pressure contact between the tube 2 and the peripheral surface, thus causing premature wear of the tube 2.
This invention has been made to overcome these deficiencies and has it as an object to provide a squeeze pump wherein the slurry may be transferred effectively, the resilient tube may be improved in durability by preventing the wear caused to the tube, and manufacture may be facilitated.
It is another object of the present invention to provide a squeeze pump wherein the tube may have improved restorability after pressing with resultingly improved efficiency of slurry suction by the resilient tube.
It is another object of the present invention to provide a squeeze pump wherein the inner peripheral surface of the pump casing need not have a ground finish and the rotary arbor may be centered roughly, resulting in the reduced manufacture costs of the overall device.
It is another object of the present invention to provide a squeeze pump wherein a rib is mounted at the center of the inner peripheral surface of the pump casing for setting the radius of bend of the resilient tube, whereby the mounting of the tube within the pump casing may be facilitated.
It is another object of the present invention to provide a squeeze pump wherein tube fatigue to be caused at the start and termination of clamping of the resilient tube may be reduced.
It is another object of the present invention to provide a squeeze pump wherein the hard materials contained in the slurry may not encroach on the inner surface of the tube during pressing of the tube by the presser rolls to prevent the wear of the tube.
It is yet another object of the present invention to provide a squeeze pump wherein the presser rolls may positively press the tube without slipping.